A drilling apparatus consisting of a power unit and a drill chuck has been known in practice for a long time, where earlier the power unit was exclusively intended for rotating the drill chuck, while opening and closing of the drill chuck had to be carried out by a drill-chuck key. Further technical development then led to drill chucks that could be activated without keys, in which a clamping sleeve could be rotated by hand relative to the chuck body fixed in place on the drill spindle so as not to rotate, in order to clamp a drilling tool between the jaws or to release the clamping effect. Furthermore, there are efforts to further simplify operation of the drill chuck, for which purpose it is proposed in the case of round jaw chucks in DE 10 2005 012 534 [US 2006/0202435] to use a coupling sleeve that is adjustable relative to the drill chuck, which sleeve is arrested by engagement with the housing to prevent rotation with it, and can be connected with the clamping sleeve with force fit, by a coupling device.